Confused about the abbreviations of the materials the bags are made of? In this article, we will explain the different materials and give you advice.
Co je to KRAFT, PET/PE nebo OPP?
Imagine immersing yourself in the fascinating world of bags - yes, the ordinary bags we use every day. What lies behind their seemingly simple construction? What secrets do they hold inside? And how do you decipher the abbreviations of the materials they are made of?
The bags that we have at our fingertips every day are the result of a clever combination of two or three different layers of materials. This combination ensures optimum properties for different applications. In the description of each bag you will find the abbreviation of the material used in its manufacture. And it is in this article that you will find the key to understanding what each abbreviation means and what unique properties each material brings.
When choosing the ideal bag for your needs, we recommend you focus primarily on its functionality and practicality. In this case, product protection always comes first and aesthetics always comes second. Take a peek into the world of bags and discover how the right combination of materials and layers can meet your expectations and make your life easier!
KRAFT - a paper layer on which recycled Japanese paper is used in most cases. It is only used for the outer layer of the bag that does not come into contact with food. The bag can be stamped or a sticker can also be used, but the sticker needs to have a thicker layer of adhesive, otherwise the sticker may peel off when the bags are filled.
PET (polyethylene terephthalate) - PET has excellent properties for food packaging, especially its tensile strength, excellent chemical resistance, light weight, good elasticity and stability over a wide temperature range (-60 to +220°C).
PETmet (polyethylene terephthalate with metallic colour) - PET film with the addition of aluminium powder (1%). The film protects against light, moisture and oxygen. The advantage is lower price than AL film.
PE (polyethylene) - PE has a low specific gravity, heat shrink and weldability, excellent resistance to water and water vapour, but on the other hand it lets gases such as oxygen, carbon dioxide and aromatics through. In most cases, it is used as an inner layer which allows the bag to be heat sealed (welding with a welder or pliers).
EVOH (ethylene vinyl alcohol) - A relatively new material that serves as a replacement for the AL layer and is fully recyclable. It is a clear film with a high barrier to gases, oxygen and moisture.
OPP (oriented polypropylene) - OPP is also similar to PE (polyethylene) in its properties. However, it is harder, stronger and more heat resistant.
OPPmat - matt finish OPP film. It provides the same properties.
CPP (cast polypropylene) - very similar properties to OPP, it has high transparency and is stronger than OPP. In most cases it is used as an inner layer which allows the bag to be heat sealed (welded with a welder or clamps).
AL (aluminium layer) - The AL layer does not come into contact with food and is placed in the middle of the three-layer film. This layer serves to prevent light, moisture and oxygen from entering the bag. It is no longer the case that the aluminium layer is the most important layer for flavour preservation. There are substitutes, namely metallized PET film or various combinations of films, e.g. BOPA+CPP.
BOPA (nylon) - the use of this film is growing. It is highly puncture resistant, provides a high barrier against gases, moisture and last but not least has a high chemical resistance. In combination with CPP or PE film , it is a full replacement for AL film. It is stable over a wide temperature range (-60 to +150°C).
PERG (GPP) - parchment paper, made from natural raw materials without the addition of chemical agents. This layer is greaseproof and waterproof.
PBS (polybutylene succinate) - compostable material (biopolymer formed by fermentation of glucose and sucrose). A bag made of this film is completely compostable, including the ZIP closure, even in a home composter. The degradability of the film is 2-6 months depending on the conditions in the composter.
Not sure which bags to choose? Contact us, we will be happy to help you.
